Atomic scale flattening and hydrogen termination of the Si(001) surface by wet‐chemical treatment

Abstract

An ultrahigh vacuum scanning tunneling microscopy has been applied to analyze wet‐chemically prepared Si(001) surfaces in an atomic scale. The surfacetreated by 2.5% HF is atomically rough and is covered by featureless corrugations resulting from an etching by OH ions in the solution. The surfacetreated by HF:HCl=1:19 mixed solution without controlling an oxide‐removal direction is also atomically rough, but is characterized by a kinkful morphology, which reflects the crystallographic nature of the Si(001) surface. On the other hand, the surfacetreated by the same mixed solution but by controlling the oxide‐removal direction is covered by regular monatomic steps and the ordered dihydride phase on the terrace. From these facts, we have confirmed that these factors, the concentration of the OH ions and the way of the oxide‐removal, play roles in the preparation of the atomically flat Si(001) surface.